After years of studies in preclinical models including GDNF-transgene infusion as well as direct GDNF protein infusion intraparenchymally or intraventricularly (Gash et al. 1996; Kells et al. 2010; Pascual et al. 2011; Richardson et al. 2011; Tomac et al. 1995), several clinical trials have been developed to investigate the efficacy of GDNF treatment in the management of PD. The gene discussed is GDNF; the disease is Parkinson disease.